Limitations to Carrier Mobility and Phase-Coherent Transport in Bilayer Graphene

We present transport measurements on high-mobility bilayer graphene fully encapsulated in hexagonal boron nitride. We show two terminal quantum Hall effect measurements which exhibit full symmetry broken Landau levels at low magnetic fields. From weak localization measurements, we extract gate-tunable phase coherence times $τ_φ$ as well as the inter- and intra-valley scattering times $τ_i$ and $τ_*$. While $τ_φ$ is in qualitative agreement with an electron-electron interaction mediated dephasing mechanism, electron spin-flip scattering processes are limiting $τ_φ$ at low temperatures. The analysis of $τ_i$ and $τ_*$ points to local strain fluctuation as the most probable mechanism for limiting the mobility in high-quality bilayer graphene.